1. Field of the Invention
The present invention relates generally to rakes for raking hay or crop residues and more particularly to rake wheels and the construction thereof.
2. Description of the Related Art
Wheel rakes have been found to be an effective farm implement for raking hay, which is generally an agricultural crop grown on a relatively even surface, evenly distributed, and cut for harvest at a consistent height, or other materials like crop residues. Crop residue, like corn stover, the residue from agricultural crops left by a previous operation, typically the harvest of grain, is being harvested more now than in the past for a variety of reasons including for use as a fuel. In the specific example of corn stover, the plants are gown in distinct rows, which results in an undulating surface, which makes raking more difficult. Even in these tougher conditions the wheel rakes are typically used to collect the material from a wide area, into a smaller windrow so that the subsequent baling operation will be efficient, although the rakes have not been designed for this more difficult condition.
Wheel rakes are typically configured as a V-rake, which can include a main frame, with a front end adapted to be hitched to a tractor. Rake arms typically supported at the back end of the main frame, are controlled such that they may be positioned adjacent the main frame in a closed or traveling position or extended in the form of a V in the opened or raking position. The V-rake is supported by a number of rolling wheels mounted on the main frame. Some configurations include additional wheels mounted on the rake arms. Each rake arm includes a number of suspension mechanisms, each supporting a single rake wheel, with four to ten or more rake wheels supported by each rake arm. The suspension mechanisms allow the rake wheels to float, to change height to follow the terrain, while maintaining a consistent weight of the rake wheel on the ground. The weight of the rake wheel on the ground is important for proper operation, the rake wheels are not powered, they rotate and move material as a result of the movement of the entire rake.
Examples of rakes of the aforementioned type are described in U.S. Pat. No. 4,324,093 issued Apr. 13, 1962 to van der Lely et al; U.S. Pat. No. 5,039,528 issued Nov. 19, 1971; U.S. Pat. No. 5,199,252 issued on Apr. 6, 1993 to Peeters; U.S. Pat. No. 5,343,643 issued Feb. 27, 1996 to Tonitti; U.S. Pat. No. 5,498,271 issued on Feb. 4, 1997 to Peeters; U.S. Pat. No. 5,699,045 issued on May 4, 1999 to Rowse et al; U.S. Pat. No. 6,220,008 issued Apr. 24 to Rowse et al and US Patent Publication 2004/0063265 published May 6, 2004 to Tonutti. All of the patents and published patent applications mentioned in this document are incorporated herein by reference in their entirety.
In addition to the description of the basic rakes, these references also describe a variety of rake wheels. Additional examples of rake wheels are described in U.S. Pat. No. 3,057,145 issued Oct. 9, 1962 to van der Lely and in U.S. Pat. No. 3,447,295 issued Jun. 3, 1969 to van der Lely, which is incorporated by reference in its entirety.
U.S. Pat. No. 3,447,295, which is incorporated by reference in its entirety, to van der Lely shows rake wheel tines passing through a rim, this patent uses the term “felly” for ref 7, that has elements made of organic elastic material to reduce stress concentrations, and reduce the risk of breakage. U.S. Pat. No. 3,447,295, in some embodiments, “vulcanizes” the metal tine to the elastic portion of the circular band and in other embodiments clamps the elastic tightly against the metal tine.
U.S. Pat. No. 3,447,295 in column 4, lines 33-39 states: “In all of the embodiments which have been described, the spokes are integral with the tines and are resiliently supported through a relatively short part of their length by organic elastic material. The organic elastic material tends to oppose resilient deformation of the spokes during use of the rake wheel so that the resilience of the tines is not excessive.” Lines 46-51 of Column 4 in the '295 patent says: “There is a tendency to substantial wear and eventual breakage at the points at which tines or their spokes extend through holes in fellys but the constructions which have been described greatly reduce or entirely avoid wear at the points just mentioned.” In summary, U.S. Pat. No. 3,447,295 recognizes “a tendency to substantial wear and eventual breakage at the points at which tines or their spokes extend through holes in fellys” and solves the problem by avoiding any friction between the tine and the felly, i.e. the '245 patent solves the friction problem by attaching plastic to the tine by vulcanization or clamping.
U.S. Pat. No. 3,057,145, which is incorporated by reference in its entirety, shows a rake wheel that includes independent bearing elements or supports 16 attached to a rim 18 and an alternate embodiment having bearing elements or supports 34 attached to a rim 39.
Although these aforementioned prior art rakes have been in use for some time, it has been found that they do not always satisfy the needs of farmers and ranchers in part due to an inherent weakness in the common construction of the rake wheels. These deficiencies are exacerbated in tougher conditions such as when raking crop residues.
Prior art rake wheel assemblies are constructed in a variety of ways to support a number of tines. In some cases the rake wheels utilize relatively short tines and the assembly is comprised of a hub with spoke structures that support an outer rim or band, with the tines mounted to and extending beyond outer rim. An example of this configuration can be found in U.S. Pat. No. 3,834,140 issued Sep. 10, 1974 to Delfino which is incorporated by reference in its entirety.
In a more common construction a rake wheel is comprised of relatively long tines attached to the hub. Two examples of wheels constructed in this manner are described in U.S. Pat. No. 4,324,093 issued Apr. 13, 1982 to van der Lely and U.S. Pat. No. 6,715,275 issued Apr. 6, 2004 to Kuehn, which are incorporated by reference in their entirety. The primary support member for the rake wheel assembly of this construction is the hub. The hub includes bearings that allow the assembly to rotate freely about a spindle. There are a variety of configurations used for the rest of the assembly, but in a typical construction the hub includes an outer disk assembly that clamps a first end of each tine. In this manner the first end of each tine is held securely such that it is not able to rotate or slide relative to the hub which thus provides the primary control for the orientation of the tines. However, the hub alone does not provide adequate support for the tines so the rake wheel assembly further includes an outer support band, felly, or rim typically made from a low carbon steel having a series of holes equally spaced around its circumference for receiving rake teeth or tines. The second, outer end of each tine slides through one of the tine support holes in the support band, which provides a relatively loose support for the tines. The support band is traditionally constructed from a bar constructed of low carbon steel with a rectangular cross section of approximately 0.1875 to 0.25 inches thick and 1.0 to 1.25 inches wide. The support band is rolled into its round shape after the tine holes are drilled in the bar. In its rolled configuration the outer support band is adequately rigid to provide support for the tines. This type of outer support band has been accepted as a component of the rake wheel assembly, providing additional support for the individual tines, by loosely connecting all the tines together, while at the same time allowing each individual tine to slide and rotate, in its tine support hole, allowing the loads, both bending and twisting, on the tines to be distributed along the entire length of the tine. This assembly has proven to be cost effective, is commercially successful as it meets the majority of the needs for farmers and ranchers, however there are some inherent problems associated with this assembly, and a need for an improved assembly.
Although the amount of relative movement between the tine and the support band is small, it is adequate, after a high number of cycles, to cause wear of both the tine and the outer support band. The operation of a wheel rake inherently subjects the tines to a high number of cycles. When the rake wheels engage the ground, which is required for operation as a result of the fact that they are ground driven, the end of each individual tine drags along the ground, which induces a force at the end of the tines. The tines are supported by the band and the hub so that the support band presses against the tines with an equal and opposite force. The tines include a bent portion so that the end of the tine, the point contacting the ground, is offset from the main portion of the tine that is supported by the support band. This offset results in generation of a torque load on the tine, resulting in a twisting action of the tine. Thus in addition to the force between the hoop and the tine, there is also relative motion caused by twisting of the tine. This combination of force and relative movement causes the tines and hoop holes to wear. After time, the tines will have a notch, created from the friction between the tines and the hoop, which causes a thin section that causes a stress riser which causes the tines to break at that point. This failure is a significant concern for this type wheel, and there is a need for an improved wheel.
There are economic advantages to making both the tines and the support bands from steel. The tines are typically made from a high carbon steel rod, while the support bands are made from low carbon steel. The practice of using similar materials exacerbates the wear. The wear of the tine is focused in a very specific area, and has been observed to cause premature failure of the tines, which is known shortcoming of rake wheels.
In addition to the wear, the relative movement, combined with the steel-on-steel contact of the tine to the support band, causes the rake wheels to create a noticeable amount of noise.
Accordingly, there is a need for an improved rake wheel, to provide improved reliability and longer life of the rake tines, and to provide quieter operation.